1. Field of the Invention
This invention relates to a method of fabricating a liquid crystal display, and more particularly to a method of fabricating a liquid crystal display that is capable of having a spacer formed at the correct position with a desired shape and height.
2. Description of the Related Art
Generally, a liquid crystal display LCD controls the light transmittance of liquid crystal cells in accordance with video signals to display a picture corresponding to the video signals on a liquid crystal display panel where the liquid crystal cells are arranged in a matrix type.
For this, the liquid crystal display includes a liquid crystal display panel where liquid crystal cells are arranged in a matrix type and a driving circuit for driving the liquid crystal display panel. The liquid crystal display panel has pixel electrodes and a reference electrode, that is, a common electrode provided for applying electric field to each liquid crystal cell.
Normally, the common electrode is formed on the entire surface of an upper substrate to be integrated while the pixel electrode is formed on a lower substrate by liquid crystal cells. Each of the pixel electrodes is connected to a thin film transistor TFT used as a switching device. The pixel electrode together with the common electrode drives the liquid crystal cell according to data signals supplied through the TFT.
Referring to FIG. 1, a conventional LCD includes an upper plate consisting of a black matrix 32, a color filter 30, a common electrode 28, a column spacer 26 and an upper alignment film 34, which are sequentially formed on an upper substrate 11; a lower plate consisting of a TFT, a pixel electrode 22 and a lower alignment film 24, which are formed on a lower substrate 1; and liquid crystal 40 interposed into an internal space provided by the upper plate, the lower plate and a column spacer 26.
In the upper plate, the black matrix 32 is formed in a matrix type on the upper substrate 11 and divides the surface of the upper substrate 11 into a plurality of cell areas where color filters 30 are to be formed for preventing light interference between adjacent cells. The color filters 30 of the three primary colors red, green, blue are sequentially formed on the upper substrate 11 where the black matrix 32 is formed. The common electrode 28, to which ground potential is supplied, is formed on the upper substrate 11 where the black matrix 32 and the color filter 30 are formed. On the common electrode 28, the column spacer 26 is formed at the area corresponding to the black matrix 32. The column spacer 26 provides a space into which the liquid crystal 40 is interposed between the upper plate and the lower plate. The upper alignment film 34 is formed to cover the column spacer 26 and the common electrode 28.
The TFT, which switches the driving of the liquid crystal cells in the lower plate, includes a gate electrode 6 connected to a gate line (not shown), a source electrode 8 connected to a data line (not shown), and a drain electrode 10 connected to the pixel electrode 22 through a contact hole. Also, the TFT further includes a gate insulation film 12 for insulating the gate electrode 6 from the source electrode 8 and the drain electrode 10, and semiconductor layers 14 and 16 for forming a conductive channel between the source electrode 8 and the drain electrode 10 by gate voltage supplied to the gate electrode 6. The TFT selectively supplies data signals from the data line to the pixel electrode 22 in response to the gate signal from the gate line.
The pixel electrode 22 is located at the cell area, which is divided by the data line and the gate line, and formed of transparent conductive material with good light transmittance. The pixel electrode 22 is formed on the protective film 18, which is spread on the entire surface of the lower substrate 1, and electrically connected with the drain electrode 10 through the contact hole, which is formed in the protective film 18. The lower alignment film 24 is spread on the lower substrate 1 on which the pixel electrode 22 is formed, and then a rubbing process is carried out to complete the lower plate.
Lastly, the upper plate and the lower plate, prepared separately as stated above, are placed in the correct position to be bonded together, then the liquid crystal 40 is interposed into a liquid crystal space prepared by the column spacer 26 and sealed to complete the liquid crystal display.
A fabricating process of the upper plate with such a composition is described in conjunction with FIGS. 2a to 2g. 
First, on the upper substrate 11 is deposited and patterned an opaque resin or an opaque metal such as chrome Cr to form the black matrix 32 as illustrated in FIG. 2a. By spreading a material, which transmits a light of a specific wavelength (red, green or blue), on the upper substrate 11 where the black matrix 32 is formed, and patterning the material, the color filters 30a, 30b, 30c of the three primary color are formed as illustrated in FIG. 2b. A transparent metal layer is deposited on the upper substrate 11, where the black matrix 32 and the color filters 30a, 30b, 30c are formed, to form the common electrode 28 as illustrated in FIG. 2c. A mixture of solvent, binder, monomer, photoinitiator etc. . . . is printed on the upper substrate 11 where the common electrode 28 is formed, and then dried. Accordingly, the solvent among the mixed materials is evaporated to form a paste 26a where the binder, the monomer and the photoinitiator etc. . . . , as illustrated in FIG. 2d. 
In the upper part of the upper substrate 11 where the paste 26a is formed, a photo mask 38 with a shielding part 38a and a transmitting part 38b is positioned, as illustrated in FIG. 2e. The paste 26a is selectively irradiated with ultraviolet radiation to be exposed via the photomask 38. If light irradiates the paste 26a through the photo mask 38, the photoinitiator is resolved to form a radical. The radical polymerizes the combinations of monomer distributed among the binders to maintain the viscosity of the exposed paste 26a. Then, the exposed paste 26a is developed by a developing solution. The non-exposed paste is then eliminated and the exposed paste remains in the paste 26a. When the remaining paste 26a is plasticized, the column spacer 26 is formed with a specific height, as shown in FIG. 2f. Polyimide is spread on the entire surface of the upper substrate 11, where the column spacer 26 is formed, to form the upper alignment film 34 on the upper substrate 11, as shown in FIG. 2g. 
The column spacer 26 of the conventional liquid crystal display takes up approximately 2% of the entire area of the upper substrate 11. This is a relatively large amount of area. Thus, the column spacer 26 is formed from 2% of the entire area of the upper substrate 11, the column spacer material is printed on the entire surface of the upper substrate 11 where the color filter 30a, 30b, 30c are formed, and the column spacer must go through exposure, development and plasticization processes.
Accordingly, the column spacer forming process is not only complicated, but the material cost and fabricating cost are also high relative to the occupied area.
In order to resolve such problems, an ink jet is used to form the spacer. The ink jet is arranged on the upper substrate 11, then the spacer material is dropped onto the ink jet to form the spacer on the upper substrate 11. However, when the spacer material falls onto the upper substrate 11 a spreading phenomenon occurs making it difficult to locate the spacer at the correct position with the desired shape and height.